(1) Field of the Invention
This invention relates to a process for manufacturing electrodes and electrodes produced thereby, and more particularly to a process for manufacturing electrochemical cathodes for use in electrochemical cells and electrochemical cathodes produced thereby.
(2) Description of the Prior Art
Metal/air batteries produce electricity by electrochemically coupling in a cell a reactive metallic anode to an air cathode through a suitable electrolyte. As is well known in the art, an air cathode is a typically sheetlike member having opposite surfaces respectively exposed to the atmosphere and to an aqueous electrolyte of the cell, in which (during cell operation) atmospheric oxygen dissociates while metal of the anode oxidizes providing a usable electric current flow through external circuitry connected between the anode and cathode. The air cathode must be permeable to air but substantially hydrophobic (so that aqueous electrolyte will not seep or leak through it), and must incorporate an electrically conductive element for external circuitry.
In present-day commercial practice, the air cathode is commonly constituted of active carbon (with or without an added dissociation-promoting catalyst) containing a finely divided hydrophobic polymeric material and incorporating a metal screen as the conductive element. A variety of anode metals are used including iron, zinc, magnesium, aluminum, alloys of aluminum, etc. Alloys of aluminum and magnesium are considered especially advantageous for particular applications owing to low cost, light weight and ability to function as anodes in metal/air batteries using neutral electrolytes, such as sea water or other aqueous saline solutions. Metal/air batteries have an essentially infinite shelf-storage life rendering them very suitable for standby or emergency uses in that the metal-air battery may be activated by addition of electrolyte.
While such an air cathode have been effective, there is a continuing desire to increase current densities at cost effective processing, etc. of such air cathode.